1. Technical Field
The present invention relates generally to data storage, and more particularly, to methods, articles, signals, and systems for efficiently backing up data.
2. Related Art
Various types of data backup are conventionally known, including tools and techniques such as: manually copying data to an Iomega® Zip® drive, a tape drive, or a floppy drive; copying data from a workstation over a local area network (“LAN”); connection to a server on that LAN; and remote data mirroring. For example, the following U.S. Patents each deal in some way with the problem of backing up data: U.S. Pat. No. 5,455,932 for a Fault Tolerant Computer System; U.S. Pat. No. 5,537,533 for a System and Method for Remote Mirroring of Digital Data from a Primary Network Server to a Remote Network Server; and U.S. Pat. No. 5,835,953 for a Backup System That Takes a Snapshot of the Locations in a Mass Storage Device That Has Been Identified for Updating Prior to Updating.
It is also known to keep a copy of data in a cache, so that later requests for the data can be serviced more rapidly than if the data were not cached. In particular and without limitation, it is well known to cache web pages and the graphics files or other files referenced by the cached pages, so that subsequent requests for those web pages and their associated files can be serviced more rapidly. Among other places, such web server caches may be located on the web server of an Internet Service Provider (“ISP”). ISPs provide individuals and/or businesses with access to the Internet and its enormous collection of web pages and other data. Many ISPs also provide access to File Transfer Protocol (“FTP”) directories, provide email facilities, and otherwise provide various services that rely on transfers of digital data across the Internet and/or another Wide Area Network (“WAN”).